Mixed super critical fluid hydrolysis and alcoholysis of cellulosic materials to form alkyl glycosides and alkyl pentosides

ABSTRACT

The present invention relates to a process for generating glucose and glucose derivatives from the direct contacting of cellulose, hemicelluloses and/or polysaccharides with a mixed super critical fluid system of alcohol and water whereby the partial pressure of the system provides for both alcoholysis and hydrolysis of the material to generate primarily glucose, and glucose derivatives.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of and claims benefit of priorityunder 35 U.S.C. § 120, to U.S. application Ser. No. 15/163,160, filed onMay 24, 2016, to issue as U.S. Pat. No. 9,605,325, on Mar. 28, 2017,which is a continuation of and claims benefit of priority under 35U.S.C. § 120 to U.S. application Ser. No. 13/882,986, filed on Jul. 31,2013, now U.S. Pat. No. 9,346,843, issued May 24, 2016, which is anational phase application claiming benefit of priority under 35 U.S.C.§ 371 to Patent Convention Treaty (PCT) International Application serialnumber PCT/US2011/058835, filed Nov. 1, 2011, which claims the benefitof priority under 35 U.S.C. § 119(e) of U.S. Provisional ApplicationSer. No. 61/409,395, filed Nov. 2, 2010. The aforementioned applicationsare expressly incorporated herein by reference in their entirety and forall purposes.

FIELD OF THE INVENTION

The present invention relates to a process for generating glucose andglucose derivatives from the direct contacting of cellulose,hemicellulose, and/or polysaccharides with a mixed super critical fluidsystem of alcohol and water whereby the partial pressure of the systemprovides for both alcoholysis and hydrolysis of the material at reducedtemperature and pressure.

BACKGROUND OF THE INVENTION

Due to the limited reserves of fossil fuels and worries about emissionof greenhouse gases there is an increasing focus on using renewableenergy sources.

Production of fermentation products from cellulose, hemicelluloses,lignocelluloses and polysaccharide containing residue materials is knownin the art and includes pre-treating followed by, enzymatic hydrolysis,weak acid hydrolysis, strong acid hydrolysis, and supercritical waterhydrolysis to generate fermentable residue materials. Acid hydrolysishas the potential to generate toxic compounds that can reduce or inhibitfermentation in addition to the consumption of substantial amounts ofacid at a significant cost. Enzymatic hydrolysis reaction rates can belong as well as sensitive to foreign materials in the target residue,and the cost of enzymes can be expensive. Supercritical water hydrolysisrequires capital cost intensive very high temperatures and pressures(>374 C and 22.1 Mpa) to achieve usable break down products. Acidhydrolysis, enzymatic hydrolysis and high pressure supercritical waterhydrolysis are challenging methodologies for generating valuable fuelsand chemicals from residue biomass. Consequently, there is a need forproviding further methods and processes for producing fermentableglucose and glucose derivative products from residue materials using atime reduced system free of acid pretreatment, enzyme technology or veryhigh pressure and temperatures to break down the cellulose linkage.

BRIEF SUMMARY OF THE INVENTION

Glucose and glucose derivates are produced from cellulose,hemicellulose, lignocellusoses and polysaccharide containing residuematerials as follows: (a) combining size reduced cellulose,hemicelluloses, lignocelluloses and polysaccharide containing residuematerials with alcohol from 0.1:1 to 100.1 by weight and water from0.1:1 to 100:1 by weight to form a slurry (b) at a temperature in arange of 140° C. to 350° C., and at a pressure in a range of 500 psig to3500 psig. (c) multiple reaction zones are established by permeablemembrane or membranes which arc used to trap the reaction mixture in thereaction zone. Once the reaction mixture of polysaccharide material issufficiently cleaved to shorter chain materials they will become solubleand small enough to pass through the reaction zone membrane thereby

mm1m1zmg reaction zone contact time (d) the reaction mixture can includehydrogen, (e) the reaction mixture can include a catalyst. The resultingreaction mixture is quenched and the un-reacted solids and nonfermentable materials are separated from the glucose and glucosederivatives by activated carbon contacting.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a method for producing glucose andglucose derivatives by performing simultaneous hydrolysis andalcoholysis on a material containing polysaccharides, cellulose,hemicellulose, lignocellulose, or combination thereof with an alcohol,water, optionally a catalyst, an optionally hydrogen.

Prior to the present invention, the conversion of biomass intofermentable sugars was a time-consuming and multi-step procedure thatwas both economically inefficient and wasteful. Additionally,conventional methods are inhibited by the presence of water, requireweak or strong acids, or the addition of expensive enzymes. In contrasta fast, single-step, and efficient method for the conversion of biomassinto sugars or sugar derivatives to produce ethanol or industrialchemicals can be performed under a mixed supercritical fluid systemwhereby the presence of both water and alcohol work in combination toachieve the alcoholysis and hydrolysis at reduced temperature andpressure.

The feedstock for this process can be for example, palm fiber, palmfruit bunches, rice husk, rice straw, corn stover, corn cobs, sugar canebagasse, switch grass, dried distillers grains (DDG) from, e.g., corn orsorghum, rice bran, eukaryota, protozoa, phytoplankton, cyanobacteria,bacteria, corn ethanol fermentation residuals, or other polysaccharideor cellulose-containing material (e.g., polysacharides, cellulose,hemicellulose, and lignocellulose) or both.

The feedstock can contain from about 0 wt % to about 100 wt % cellulosicmaterial (preferable less than about 70 wt %, but at least about 1, 5,10, 15, 30 wt %). Each of the amounts for the feedstock componentslisted above is based on the dry weight of the feedstock.

The feedstock can be un-extracted meaning that it has not been purifiedto remove certain components (e.g., water, salt, foreign matter, ormixtures thereof). For example, the feedstock can contain at least about5 wt % sails and up to 50 wt % salts. The feedstock can also be purified(e.g., a purified cellulose or paper pulp material). The feedstock cancontain husks, shells, or other materials that are grown by thefeedstock source other than the feedstock. The feedstock, prior toreaction, can be dried but the feedstock is preferred wet. The feedstockcan be ground to reduce its particle size prior to reaction.

For purposes of this description, rice husk, rice straw, corn stover,wheat straw, corn cobs, sugar cane bagasse, switch grass, and woodybiomass are used as the feedstock, however those skilled in the artwould understand that other feedstock can be used. Also, the overallprocess, is as indicated, applicable to the other feedstocks withadjustments to the process configuration.

In addition, with other feedstocks, there may be some variations in thesuper critical alcoholysis and hydrolysis chemistry such that alternateco-products are formed in the reaction. For example, with a highcellulose feed (e.g., at least about 1, 5, 10, or 15 wt % but less thanabout 50, 60, 80 or 100 wt % based on the dry weight of the feedstock)there may be further conversion of that component to derivatized sugarcompounds such as alkyl glucosides and 5-hydroxymethylfurfural. Forexample, when a solution of glucose in methyl alcohol is saturated withhydrochloric acid a crystallizable compound having the formulaC₆H₁₁O₆CH₃, is formed.

A similar reaction takes place with all of the alcohols which arecapable of dissolving glucose, such as methane, ethanol, propanol,butanol and their isomers, and the compounds formed correspond tonatural glucosides. The sugar entering into the reaction need notnecessarily be glucose, so that a number of such artificialalcohol-derivatized sugars can be prepared. The hydrochloric acid of thereaction to produce derivatized sugars can also be replaced by anotheracid such as H_(s)SO₄. These derivatized sugars, when boiled with diluteacid, react with water and are decomposed into the sugar and alcohol. Inaddition, further derivatization, in the presence or absence of acid ora catalyst, at the higher ranges of temperatures and pressures can leadto valuable products from the sugars such as methyl glucosides, ethylglucosides, 5-hydroxymethylfurfural, levulinic acid, formic acid, andesters thereof. The categorization of each feedstock may be necessary todetermine the best process splits and optimal end-products.

The alcohol for the invention can be, for example, methanol, ethanol,propanol butanol, isopropyl alcohol, sec-butanol, t-butanol, benzylalcohol or combination thereof. From a practical standpoint, and forgeneral fuel and potential downstream chemical considerations, alcoholscontaining from 1 to 5 carbons would be preferred, however, there may bespecific situations and conditions wherein higher alcohols could beused. Testing with a specific alcohol would readily determine theamenability of a particular alcohol. Again, for purposes of thisdiscussion, methanol is used us the alcohol, however those skilled inthe art would understand that other alcohols can be used.

The feedstock can be ground to reduce its particle size and is thentransferred to the Direct Mixed Supercritical Fluid Reactor systemwherein the feedstock is mixed with the selected alcohol (e.g.,methanol) and water. The amount of alcohol and water can vary, but wouldtypically be sufficient to allow for a slurry mixture using equal pansof alcohol and water. This typically provides sufficient excess alcoholand water for the reaction noting that typically 30% by weight alcoholof the liquid mixture to 70% by weight water are required to achievesuper critical partial pressure, under super critical conditionsalcohols, e.g. methanol. Preferably, the alcohol should be in an amountfrom about 10% by wt % to about 1000% wt % of the water, preferably fromabout 20% by wt % to about 500% wt % of the water and most preferablyfrom about 50% wt % to about 300% wt % of the water. Higher alcoholswould require a higher weight percentage of alcohol. For practicaloperation, the amount of alcohol would normally be in the range of about25 wt % to 300 wt % of the dry feedstock and preferably in the range ofabout 50 wt % to about 200 wt % of the dry feedstock.

The temperature of the reaction is in a range of about 240° C. to about320° C., about 240° C. to about 270° C., or about 250° C. to about 280°C. The pressure of the reaction is a range of about 500-3200 psig. fromabout 1000-2000 psig, or from about 1500 to 2000 psig.

The reaction mixture before reaction can also contain water in anamount, of at least about 5 wt % of the dry weight of the feedstock, atleast about 10 wt % of the dry weight of the feedstock, at least about40 wt % of the dry weight of the feedstock, at least about 70 wt % ofthe dry weight of the feedstock, or at least about 100 wt % of the dryweight of the feedstock or at least about 200 wt % of the dry weight ofthe feedstock.

The reactor system can be batch or continuous. There are severalconventional pressure vessel systems available that will operate inbatch and continuous modes and the process lends itself to the“conventional” methods for this stage. In the continuous plug flow orcontinuous stir tank configuration a permeable membrane is used to trapthe reaction mixture in the reaction zone to minimize resonance time inthe zone. In addition, a continuous pipe-type reactor can be used tocarry out the reaction. The reactor is a pipe with sufficient residencetime to allow for the reaction to complete and is operated under thetarget pressure and temperature range. The pipe allows for reasonablereaction to occur with minimized vessel complexity. In addition the pipecan contain zones separated by membranes whereby the reaction mixturewill flow to the next contact zone after size reduction via hydrolysisoccurs. This minimizes residence time in the reaction zone and reducesby-product formation.

The reaction can be carried out for a period of about 0.25 minutes to240 minutes and the reaction time can depend on the selected reactionsystem and operating temperature. In a conventional stirred tankreactor, the reaction time can be in the range of 60 to 90 minutes for abatch reactor. At higher temperatures, and corresponding pressures, thereaction time can be reduced.

The reaction mixture can include hydrogen and can include a catalyst.The hydrogen can range from 1:1 mole wt of the glucose in the feedstockto 1000:1 mole wt of the contained glucose in the feedstock. Thepresence of hydrogen and/or a hydrogenation catalyst in the reactionmixture improves stability of the glucose by forming sorbitol or otherpolyhydric alcohols and sugar derivatives. Catalysts can beheterogeneous or homogenous. Catalysts metals can include platinum,palladium, rhodium, ruthenium, rainey nickel, and copper chromite.

The reaction product slurry typically consists of any unreactedfeedstock, glucose, alkyl glucosides, sorbitol, excess alcohol, water,lignin, organic salts, inorganic salts, etc. The resulting glucose andalkyl glucosides will be in the range of 10-70 wt % of the productslurry. The reaction slurry is transferred to a Liquid/Solid Separationsystem. In this step, the liquid fraction is separated from theinsoluble solids portion, including any lignin if continued in the feed.Separation can be carried out using any number of standard separationtechniques, such as filtration, carbon treatment, centrifugation,combinations of each approach, and the like. Slight washing of thesolids, in the separation device, can be carried out with a small amountof the alcohol, water, or hydrophobic solvent. The target glucose andalkyl glucoside materials remain with the liquid water phase.

The washed solids are then sent to storage for re-processing ordischarge.

The alcohol and water is removed from the soluble fraction containingthe glucose and alkyl glucoside by evaporation, centrifuge separation,crystalization or other method obvious to someone skilled in the art.The alcohol water mixture is then recycled back to the reaction mixturevessel where make up alcohol and water is added and new target feedstocki added.

The resulting glucose and methyl glucoside fraction is transferred tostorage.

The alkyl glucoside can be optionally hydrolyzed using weak acid andadditional water. The resulting mixture would be glucose and alcohol.The alcohol would be removed by evaporation, centrifuge separation,crystalization or other method obvious to someone skilled in the art.

The resulting glucose fraction is transferred to storage.

The glucose and/or glucose and alkyl glucoside then enters aFermentation System wherein it is mixed with conventional fermentationreagents, e.g. yeasts, etc., then allowed to react in a conventionalfashion. Information, relative to the conventional processing approachesare available on numerous web-sites, and a significant resource is theRenewable Fuels Association (available on the WorldwideWeb at rfa.org),which is the key industry trade association. The main advantage is thata potentially lower cost feedstock has now beat made available that doesnot involve a current agricultural food source commodity but rathersecond generation non food materials such as cellulose or agriculturalby-products.

The fermentation slurry is then sent to a Solid/Liquid Separationsystem, and the non-fermented solids removed from the liquid (beer)phase. Again, conventional separation methods may be utilized, such asfilters, centrifuges, and the like. The solids fraction can then be usedelsewhere e.g. return to the algae farms as a supplemental food source.

The fermented liquid is transferred to an Evaporation System wherein thealcohol phase is evaporated from the liquid, along with some water.

The alcohol fraction is next treated in a Distillation/Molecular Sievesystem. In this process step, the aqueous alcohol is first distilled, toproduce a nominal 95% ethanol material, then processed in a molecularsieve unit to remove the remaining water and produce a 99.5%+ ethanolproduct (31). This operation is conventional and widely used in thecurrent ethanol production industry.

The residual solids from the fermentation stage may containnon-fermentable materials that may also contain significant levels ofuseful proteins or amino acids. This solids fraction could be combinedwith other animal feed products or, depending on the exact nature of thematerial (based on the feedstock), further processed, via drying, toproduce a specialized feed product.

Example 3 Corncob (Corn Feedstock)

Corn cobs are a major co-product from the production of corn starchesfor fermentation into ethanol. Corn cobs are the material remainingafter the corn kernels are removed. Much of this material is plowed backinto the field as a nutrient component, soil amendment, or burned forenergy recovery.

The quantities of this material are significant. For example, a typicalacre of corn will yield 160 bushels of corn and 1200 pounds of corncobs. In 2010 the U.S. corn acreage was estimated at 90 million tonswhich will generate over 49 million tons of cobs. In general, the cobsfrom corn contains about 45% cellulose, and 40% hemicellulosescarbohydrate (which if properly prepared could serve as a fermentationfeed) generating 38 million tons of cellulose derived glucose, non foodfeed stocks for fermentation into ethanol.

It should be noted that with preparation, the resulting sugars consistof both C6 (hexose) and C5 (pentose) fractions. The C6 fraction isfermentable via the use of standard yeast materials. C5 sugars will notferment with yeasts only, and specialized organisms have been developedthat will convert C5's. In addition, there are other processes that havebeen developed that utilize C5 sugars to produce other (non-ethanol)products.

Significant advantages could be brought about in the biofuels industriesif this feedstock could be processed to generate ethanol. Incorporationof corn cob treatment operations within existing ethanol plants couldfurther enhance the potential economic attractiveness.

To assess the potential for the process to handle this feed, samples ofcorn cob granule material were collected from Grit-a-Cob, a corn cobmaterial sold as a sand blasting media. The basic testing approach wasas follows:

-   -   The corn cob granules were further ground to a particle size of        400 mesh to allow for ease of feeding as a slurry to the        continuous reactor system 100 g of cob material was mixed with        100 g methanol and 100 g water then reacted at 280 C and 2100        psi for 30 minutes.    -   After reaction, the glucose and methyl glucoside product mass        was then filtered and washed with water to separate unreacted        solids from the glucose and methyl glucoside (and other) bearing        liquid.    -   The solids fraction was then set aside.    -   The liquid fraction was then heated to remove excess alcohol        (that would be recovered for recycle in a commercial scenario).    -   With the reaction conditions employed, derivatized sugars, such        as 5-hydroxymethylfurfural, could be formed which will allow for        potential production and recovery of other products.

The reaction mixture was analyzed on an HPLC device and results showedthe presence of glucose and methyl glucoside.

Example 4; Rice Husk

Rice husk is a major residue from the production of rice for food. Ricehusk is the material remaining after the rice kernel and rice bran areremoved. Much of this material is waste that is piled, dumped or buntedfor energy recovery.

The quantities of this material are significant. For example, in 2010the world rice acreage was estimated at greater than 475 million tonswhich will generate over 104.5 million tons of husk. In general, thehusk from corn contains about 35% cellulose, and 25% hemicellulosescarbohydrates (which if properly prepared could serve as a fermentationfeed) generating roughly 60 million tons of cellulose derived glucose,non food feed stocks for fermentation into ethanol.

It should be noted that with preparation, the resulting sugars consistof both C6 and C5 fractions. The C6 fraction is fermentable via the useof standard yeast materials. CS sugars will not ferment with yeastsonly, and specialized organisms have been developed that will convertC5's. In addition, there are other processes that have been developedthat utilize CS sugars to produce other (non-ethanol) products.

Significant advantages could be brought about in the biofuels industriesif this feedstock could be processed to generate ethanol. Incorporationof rice husk treatment operations within existing ethanol plants couldfurther enhance the potential economic attractiveness.

To assess the potential for the process to handle this feed, samples ofrice husk material were collected from Wilmar Company, one of theworld's largest rice producers and palm products. The basic testingapproach was as follows:

-   -   The rice husks were further ground to a panicle size of 400 mesh        to allow for ease of feeding as a slurry to the continuous        reactor system. 100 g of rice husk material was mixed with 100 g        methanol and 100 g water then reacted at 280 C and 2100 psi for        30 minutes.    -   After reaction, the glucose and methyl glucoside product mass        was then filtered and washed with water to separate unreacted        solids from the glucose and methyl glycoside (and other) bearing        liquid.    -   The solids fraction was then set aside.    -   The liquid fraction was then heated to remove excess alcohol        (that would be recovered for recycle in a commercial scenario).    -   With the reaction conditions employed, derivatized sugars, such        as 5-hydroxymethylfurfural, could be formed which will allow for        potential production and recovery of other products.

The reaction mixture was analyzed on an HPLC device and results showedthe presence of glucose and methyl glycoside.

We claim:
 1. A method for making and hydrolyzing an alkyl glucoside themethod comprising: (a) (i) combining a feedstock with an alcohol andwater, wherein the feedstock comprises a cellulosic material, or acellulosic material and a protein; or (ii) combining a feedstock with analcohol and water, wherein the feedstock comprises a cellulosicmaterial, or a hemicellulose-comprising material, or both a cellulosicmaterial and a hemicellulose-comprising material: and (b) reacting thefeedstock of (a) and the alcohol and water at a temperature in the rangeof between about 140° C. and 350° C., and at a pressure in a range ofbetween about 400 psig and 3500 psig to cleave the cellulosic materialto generate a reaction product comprising an alkyl glucoside: and (c)hydrolyzing the alkyl glucoside using a weak acid and additional water,wherein the resulting mixture is a glucose and an alcohol, wherein: (i)the feedstock comprises at least about 10 wt % cellulosic material basedon the dry weight of the feedstock; (ii) the feedstock comprises atleast about 10 wt % proteins based on the dry weight of the feedstock;(iii) the water content of the combination of (a) before reaction isbetween about 30 wt % and 300 wt % of the dry weight of the feedstock;(iv) the water content of the combination of (a) before reaction is atleast about 70 wt % and the alcohol content of the combination of (a)before reaction is at least about 30 wt %; or (v) the feedstock furthercomprises a hexose or a pentose, and the alcohol is in an amount frombetween about 0.5% and 350% wt excess of the hexose or the pentose inthe feedstock.
 2. The method of claim 1, wherein the feedstock comprisesat least about 10 wt % cellulosic material based on the dry weight ofthe feedstock.
 3. The method of claim 1, wherein the feedstock comprisesat least about 10 wt % proteins based on the dry weight of thefeedstock.
 4. The method of claim 1, wherein the water content of thecombination of (a) before reaction is between about 30 wt % and 300 wt %of the dry weight of the feedstock.
 5. The method of claim 1, whereinsaid feedstock comprises: (a) rice husk, rice bran, corn stover, corncobs, sugar cane bagasse, palm fiber, palm kernel cake, wood pulp, pinetree material, fir tree material, hardwood tree material, switch grass,microalgae, macro algae or cyanobacteria, or any combination thereof; or(b) a cyanobacteria, a lignocellulose, a cellulose, a polysaccharide, orany combination thereof.
 6. The method of claim 1, wherein the alcoholcomprises a methanol, ethanol or propanol, or any combination thereof.7. The method of claim 1, wherein the alcohol is in an amount frombetween about 0.5% and 350% wt excess of the hexose or pentose in thefeedstock.
 8. The method of claim 1, wherein the reaction of thefeedstock, water and the alcohol is performed under conditionscomprising a hydrogenation catalyst.
 9. The method of claim 8, whereinthe hydrogenation catalyst comprises a heterogeneous catalyst or ahomogenous catalyst.
 10. The method of claim 1, wherein the temperatureis in the range of between about 180° C. and 350° C.
 11. The method ofclaim 1, wherein the temperature is in the range of between about 240°C. and 350° C.
 12. The method of claim 1, wherein the pressure is in therange of between about 500 psig and 3200 psig.
 13. The method of claim1, wherein the pressure is in the range of between about 1500 psig and3500 psig.
 14. The method of claim 1, further comprising removing thealcohol, optionally removing the alcohol by evaporation, centrifugeseparation or crystallization.
 15. The method of claim 8, wherein thehydrogenation catalyst comprises a catalyst metal.
 16. The method ofclaim 15, wherein the catalyst metal is selected from the groupconsisting of a platinum, a palladium, a rhodium, a ruthenium, a raineynickel and a copper chromite.
 17. The method of claim 1, wherein thereaction product is in the form of a reaction product slurry having aninsoluble solids portion and a liquid fraction.
 18. The method of claim1, further comprising separating or isolating the alkyl glucoside fromthe reaction product of the reaction of (b).
 19. The method of claim 18,wherein the method for separating or isolating the alkyl glucosidecomprises: transferring the reaction product slurry to a Liquid/SolidSeparation system to separate the liquid water phase fraction from theinsoluble solids portion, including any lignin if contained in the feed,wherein glucose and alkyl glucosides remain with the liquid water phasefraction, and optionally separating the liquid water phase fraction fromthe insoluble solids portion comprises use of filtration, carbontreatment, centrifugation or a combination thereof, and optionally theinsoluble solids portion is washed with alcohol, water or hydrophobicsolvent and sent to storage for re-processing or discharge.
 20. Themethod of claim 1, wherein the feedstock further comprises a hexose or apentose, and the alcohol is in an amount from between about 0.5% and350% wt excess of the hexose or the pentose in the feedstock.
 21. Themethod of claim 1, wherein the water content of the combination of (a)before reaction is at least about 70 wt % and the alcohol content of thecombination of (a) before reaction is at least about 30 wt %.